SU975834A1 - Method for installation of hearth of aluminium electrolyzer - Google Patents

Description

The invention relates to ferrous metallurgy, in particular to the electrolytic production of aluminum.

A known method of mounting the bottom of an aluminum electrolysis cell, including the laying of coal blocks and packing interconnect seams carbon-containing charge [1].

The disadvantage of this method is the formation of cracks in the interblock joints during shrinkage during firing of the hearth, which reduces the grade of aluminum produced and the lifetime of the electrolyzer.

There is also known a method of mounting the bottom of an aluminum electrolysis cell, according to which the interblock joints are packed in layers, the lower layer, consisting of up to one third of the block height, is filled with anthracite hearth, and the upper layer is crushed by the fight of coal blocks [2].

The disadvantage of this layer-by-layer method of mounting the hearth is that cracks are formed in the lower layer of the seam, and in the upper one the necessary mechanical strength is not ensured, which ultimately leads to the destruction of the hearth and decrease

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quality of aluminum due to the dissolution of steel current-carrying rods.

This occurs because the suture compounds from the anthracite bottom mass, as heterogeneous systems, have a non-uniform structure. The heterogeneity of the structure of the suture connection concerns not only the composition. Arising during coking seams shrinkage and thermal stresses concentric ruyutsya ₁₀ preferably at interfaces coke charge phase - the lateral surface of the carbon block. Due to the presence of stress concentrations in the seams, the connection between the hearth block and the seal is weakened. The weakening of the bond is the higher

¹⁵ the greater the width of the interconnect seams. During the formation of the coke structure in the coke charge in the process of burning the bottom, the absolute linear shrinkage of the seam joint increases as the bond between the coal block and the seal decreases. The increase in absolute linear shrinkage of the seams contributes to the formation of cracks in the central and peripheral hem seams. So, if used by 3

four

975834

With a relative shrinkage of 0.5%, then with its cohesive force with a coal block of 8 and 16 kgf / cm ^2, 5 and 1.2 mm cracks are formed in the joints, respectively.

When filling the bottom seams with a dry mixture, it is possible to avoid shrinkage of the joint material and the formation of shrinkage cracks. However, due to the absence of binding components (pitch) in the dry mixture, the required mechanical strength of the seam joints is not ensured.

The aim of the invention is to increase the service life of the hearth and increase the grade of the resulting aluminum.

This goal is achieved by the fact that according to the method of mounting the bottom of the aluminum electrolysis cell, including the laying of coal blocks and the layer-by-layer packing of the inter-block joints with a carbon-containing mixture, carbon reinforcing inserts are introduced into each layer.

The introduction of carbon reinforcement inserts eliminates the absolute linear shrinkage of the seam and the formation of cracks in it. Absolute linear shrinkage of the seam is eliminated due to the fact that reinforcing carbon inserts have a positive temperature coefficient of linear expansion, while coke-batch charge has shrinking properties when heated.

Example. The bottom with the installed bottom blocks (cathode sections) and the mounted side lining was cleaned of the remnants of building materials (brick, battle, blocks, etc.), blown with compressed air and heated the surface to 150 ° C. The heated hearth mass was poured into the seams and compacted with pneumatic tampers to obtain a layer of heels with a height of 100 mm. In the layer of heels impose

indented prismatic carbon inserts 150 mm long, 30 mm wide and 100 mm high. Indentation was carried out by a portable hydraulic press. By

5 the length of the seam insert was set apart from each other at a distance of 40-60 mm. In order to form the next layer of a heel with a height of 100 mm, the heated bottom mass was filled into the seams, sealed it, and ¹⁰ carbon inserts were again inserted into the same reinforcing carbon. In the process of mounting the bottom of the aluminum electrolysis cell, four layers of beadings were sewed along the height of the seam with their prismatic coal inserts flashing.

₁₅ According to the proposed method, two electrolysers are mounted. Both electrolyzers work in a steady technological mode and give the highest grade metal for 7 months.

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Claims (1)

Claim A method of mounting the bottom of an aluminum electrolysis cell, which includes laying coal blocks and layer-by-layer packing of interblock joints with a carbon-containing charge, characterized in that carbon reinforcements are introduced into each layer to increase the service life of the bottom and increase the grade of the aluminum produced.